When lumber is dried, it is desirable from the viewpoint of efficiency that as much lumber as possible be dried simultaneously in a drying kiln, and a variety of loading devices for that purpose are now in use.
When the drying process is finished, however, there is still another process needed; that is, getting the pallet supporting the lumber out of the kiln and unloading the dried lumber off the pallet. This operation is in most cases manually performed, since the lumber is much lighter after drying. Still, much labor is needed for doing the job. Hence, the unloading process is also desirably to automated. However, installing an unloading machine in addition to a loading machine in a factory will cost an additional amount of money, and factory owners will have to make excessive investment in facilities.